Generally, acknowledge-back selective call receivers transmit information at a low data rate, typically 50 to 100 bits-per-second. The higher the number of bits used, the greater the probability of error, and especially at such a low data rate, one additional bit may result in a substantial increase in the received error rate. Thus, to ensure a reasonable error rate at this low data rate, the number of bits-per-transmission must be few.
Additionally, for known call-initiated portable transceiver systems, the portable transceivers transmit their addresses along with their initiation signals to a base site to enable the base site to determined which portable transceiver is requesting communication. A typically call initiated portable transceiver system, for example, a call initiation acknowledge-back pager within a paging system comprises a plurality of call initiation acknowledge-back pagers and at least one base site. The base site receives calls initiated by each of the call initiation acknowledge-back pagers which may be coupled to a public telephone network for establishing communication. The transmission of the address of the call initiation acknowledge-back pagers substantially increases the number of bits transmitted for a call initiation signal. This increase in the number of bits exacts a high penalty on the received error rate. Furthered by the unsynchronized and random fashion of call initiation signals, a system having a plurality of call initiation acknowledge-back pagers will suffer numerous collisions between call initiation signals. A collision is the simultaneous arrival of at least two call initiation signals at a base site from at least two call initiation acknowledge-back pagers. As a result, the base site cannot distinguish between the call initiation signals. Thus, a need exists for reducing the number of collisions between call initiation signals to improve the resulting error rates.